This invention in general relates to electrical safety devices and in particular to a gated electrical safety outlet, i.e., an electrical outlet in which a xe2x80x9cgatexe2x80x9d or xe2x80x9cblocking memberxe2x80x9d is provided to ensure that a person cannot receive an electrical shock by inserting an object into the outlet and contacting its live internal receptacle.
It has long been recognized that conventional electrical outlets pose a safety hazard because it is possible for a person to insert a narrow electrical conductor, such as a paper clip or screwdriver, through the xe2x80x9clivexe2x80x9d aperture intended to accommodate the live prong of an electrical plug and thus contact the live internal receptacle lying behind this aperture to cause an electrical shock that is potentially fatal. Although young children are especially exposed to this hazard, it not unknown for adults working near an electrical outlet to let a screwdriver or similar tool inadvertently enter the aperture to cause an electrical shock.
Several approaches have been taken to remove or reduce this serious safety hazard. In homes with young children, it is common practice to xe2x80x9cchildproofxe2x80x9d electrical outlets which are not in use by inserting non-conducting plastic safety devices which have prongs arranged to be gripped by the receptacles of the outlet and a cover plate which completely covers all the apertures of the outlet. Although this approach is effective in principle, it suffers from several practical disadvantages. The safety devices must be removed before an outlet can be used and replaced immediately after use of the outlet is concluded. A busy, perhaps distracted, parent can easily forget to replace the safety device. In addition, such devices being small and light weight are easily lost; especially, for example, on a crowded kitchen work surface. Hence, once removed, such small devices, if left unattended on a counter or floor, can be picked up by small children and become a different kind of hazard if the child places it in his or her mouth. It is also not unknown for the prongs of such devices to break off after repeated use, thus rendering the outlet unusable until it is disassembled and the broken prong removed. A modern single family house may have more than 60 outlets (counting both parts of the conventional double outlet separately), and locating all the outlets and providing them with individual safety devices is no small task, especially since young children are adept at finding outlets in places (for example in narrow spaces below furniture) which are inaccessible to adults. Finally, and perhaps most importantly, even though families with young children will put up with all the aforementioned problems, it is unreasonable to expect similar tolerance in the homes of grandparents, aunts, uncles, other relatives or simply friends and neighbors, where young children are present only occasionally.
The aforementioned disadvantages of removable safety devices indicate a need for a form of safety device which is permanently installed within an electrical outlet so that it blocks attempts to introduce foreign objects into the live aperture of the outlet (thus preventing such foreign objects contacting the live receptacle and giving the person holding the object an electric shock) but permits an electrical plug to be inserted into the outlet in the normal manner. For example, electrical power strips are known which comprise a plug, an extension cable one end of which is connected to the plug, and an outlet block connected to the opposed end of the cable, one surface of this outlet block forming a face plate and bearing a plurality of electrical outlets. In some such power strips the outlets are equipped with blocking members or gates installed behind the face plates of the electrical outlets. Each blocking member is normally in a closed position in which its blocks its associated outlet but has a projection which extends through a side surface of the outlet block so that the blocking member can be moved manually sideways to an open position to open the outlet and permit a plug to be inserted therein in the normal manner. The blocking member is provided with biasing means so that when the plug is removed from the outlet, the blocking member moves back to its closed position.
Unfortunately, this type of blocking member or xe2x80x9cgatexe2x80x9d is not readily applicable to conventional wall mounted electrical outlets, where the face plate is essentially flush with the surrounding wall surface, since in such outlets it is not possible to provide manual access to the periphery of the blocking member, as required to allow manual movement of the blocking member to open the outlet. Furthermore, it is not practical to modify such a blocking member by providing a manually-movable extension which projects through the face plate. Such a modification would require a non-standard face plate and many people desire to use standard form but colored or otherwise decorated face plates to match room decor. More importantly, it is today common practice to insert into electrical outlets devices which lie flat against portions of the outlet extending well beyond the openings through which plugs are inserted into the outlets. Examples of such devices include power bricks (step-down transformers/rectifiers used to supply low voltage direct current to power portable computers and other consumer electronics) and surge suppressor adapters. Thus, any requirement to change the external form of an electrical outlet is likely to be unacceptable to many consumers.
In view of the foregoing, it is a primary object of the present invention to provide an electrical outlet which blocks attempts to introduce foreign objects into the outlet in a manner which risks giving the person holding the object an electric shock but which permits an electrical plug to be inserted into the outlet in the normal manner. In particular, it is an object of the present invention to provide such a protected electrical outlet which does not require removal of a member from the outlet before a plug can be inserted therein.
It is a further object of the present invention to provide such a protected electrical outlet which has the same external form as a conventional unprotected outlet, thus permitting the protected outlet to accommodate any electrical device which can be accommodated by the unprotected outlet.
It is an object of the present invention to provide a protected electrical outlet which does not require the use of special plugs.
It is also an object of the present invention to provide a gated electrical outlet which is resistant to being opened by an object inserted into its live aperture.
Other objects of the invention will be apparent and will appear hereinafter in the following detailed description when read in connection with the drawings.
This invention provides an electrical outlet adapted to receive an electrical plug having at least live and neutral prongs of equal length. The outlet comprises a support member having an outer surface, an inner surface and at least live and neutral apertures extending from the outer surface to the inner surface of the support member; a live receptacle adapted to receive the live prong and spaced from the inner surface of the support member adjacent the live aperture therein; and a neutral receptacle adapted to receive the neutral prong and spaced from the inner surface of the support member adjacent the live aperture therein. The support member and the live and neutral receptacles are arranged so that the live and neutral prongs of the electrical plug can be inserted through the live and neutral apertures, respectively, in the support member and enter the live and neutral receptacles, respectively. The outlet further comprises a blocking member disposed between the inner surface of the support member and the receptacles. The blocking member is movable between a closed position, in which it blocks the live and neutral apertures in the support member, and an open position, it which it does not block the live and neutral apertures, thereby permitting the live and neutral prongs of the electrical plug to pass through the live and neutral apertures, respectively, in the support member and enter the live and neutral receptacles, respectively. The blocking member has biasing means for biasing the blocking member towards its closed position; a cam surface disposed adjacent the neutral aperture and arranged to be engaged by the neutral prong passing through the neutral aperture so that contact between the neutral prong and the cam surface causes the blocking member to move to its open position. The blocking member also has a recess arranged so that, when the blocking member is in its closed position, the recess lies adjacent the live aperture such that a portion of the live prong can be accommodated within the recess while the blocking member is still in its closed position.
The terms xe2x80x9cinnerxe2x80x9d and xe2x80x9couterxe2x80x9d are used herein with reference to the direction of movement of a plug being pushed into the outlet. Thus, the outer surface of the support member is that which is visible when the outlet is installed, the prongs of the plug passing first through this surface of the support member. Terms such as xe2x80x9cextending inwardlyxe2x80x9d etc. are to be construed in a similar manner.